Various methods and devices are known from the prior art for the transferring of graphical designs or inscriptions to flat surfaces (printing presses, computer printers, etc.). These devices are mostly designed to work with specific media, such as e.g. paper or films, specific formats, and specific surface treatment methods. Flat subsurfaces often present themselves as potential carriers for graphical information, and in particular advertising messages; such information may be e.g. glued or painted onto the surface in question. Devices capable of printing or otherwise acting directly on various types of surfaces such as e.g. concrete, glass, or grass are generally constructed as portable devices, which are guided, automatically or manually, across the generally static surface to which a design is to be applied.
DE 198 20 149 A1 and DE 10 2005 030 686 A1 depict a method for the automated generation of complex patterns or inscriptions on surfaces of various kinds, in which a device travels over the surface and transfers a design to it e.g. by the controlled direction of spray nozzles.
For smaller surfaces, graphic designs with more delicate structures or patterns are often still applied directly by hand, such as in the use of stencils for producing designs on walls or written text on baked goods. DE 10 2009 0011 489 A1 describes a method in which, with the aid of a stencil, graphical patterns can be created through the alteration of cleaned and not cleaned surfaces, such that the patterns are temporary in nature and do not damage the underlying surface.
For larger surfaces, manual treatment is too inconvenient. As an example, boundary lines for an athletic field are applied to a high-quality grass surface by machines which spray or deposit material using an operating principle similar to that of a printer.
The application of a design to the surface is carried out in this case by means of a series of actuators and a path-guided process. A device comparable to a print head travels across the surface to be marked, with the printing position e.g. arrived at manually, or the positioning carried out by means of a guide strip or a positioning system based on a transmitter beacon. Marking devices may also be controlled with modern laser systems (EP 1 760 428 A1).
Patterns of stripes can also be created e.g. through rolling of the lawn during mowing, by manual adjustment of the cutting height, or through alternating the direction of mowing.
For the application of designs to smaller grass surfaces, DE 202 11 649 U1 describes a circle/spiral area lawnmower in which an integrated circuit with an active winding unit continually alters the radius to be mowed by a self-propelled battery-powered lawnmower such that patterns may be created.
EP 1 655 709 A1 shows a method for the use of grass surfaces as advertising space. In this method, the grass surface is temporarily pressed down with weights, and a pattern may be created with non-flattened blades of grass using gaps or recesses in the weighting.
A patterned grass surface can also be created through planting different types of grass, in accordance with AT 410 401 B.
The prior art suffers from several disadvantages: Accurate positioning of automatically guided, self-propelled devices can only be achieved with the aid of external auxiliary devices, such as direction-finding devices or marking elements, or by means of costly or complex position-finding methods.
Standard movable devices, such as lawnmowers or spraying machines, are primarily designed to apply designs to level field and grass surfaces.
The application of a three-dimensional surface treatment is difficult on uneven surfaces, as mobile systems, such as lawnmowers, constantly change their point of reference in traveling across the surface on which they are working The change in distance from the surface resulting from surface elevations and depressions is not compensated for in devices designed according to the prior art by an adjustment to the cutting height.
The object of the invention is thus a device and a method with which simple patterns and also complex design elements (graphics, logos, script, reliefs) can be automatically applied, precisely and economically and without additional auxiliary positioning devices, to smaller and larger field and grass surfaces alike. The method should also be suited for use on inclined surfaces, as these are particularly visible.